Try this:
main.cpp
#include <QtSerialPort/QtSerialPort>
#include <iostream>
int main()
{
QSerialPort serialPort;
serialPort.setPortName("yourportpath"); // Hard code it for a test
if (!serialPort.open(QIODevice::ReadOnly)) {
std::cout << "Error: " << serialPort.error() << std::endl;
return 1;
}
return 0;
}